In the field such as a server, there has been a growing need for high-speed access to massive data such as those in databases (DB) in the coming era of big data. Given delays in three-dimensional memory mounting technology (TSV), that need has yet to be met by a trend of main storages getting ever-larger capacities, each of main storage being made up of DRAMs (Dynamic Random Access Memory). Moreover, there exists a difference of approximately 106 in throughput (latency) between the DRAMs and SSDs (Solid State Drive) or HDDs (Hard Disk Drive) serving as auxiliary storages connected through SAS (Serial Attached SCSI).
Commercial production is expected of SSDs (PCI-SSD) connected through PCI (Peripheral Component Interconnect Express) and having a response speed between DRAMs and SSDs (SAS-SSD) connected through SAS. The market of the SSDs (PCI-SSD) is also expected to expand.
As a result of a prior art search conducted after the present invention was made, Patent Document 1 was extracted as a related document. Patent Document 1 discloses an FBDIMM (Fully Buffered DIMM) in which flash memories and DRAMs mounted on different DIMMs (Dual Inline Memory Module) are connected in the daisy-chain style via serial transmission buffer elements mounted on each module in a serial transmission system. In accordance with the FBDIMM signal transmission protocol, memory controllers transmit serialized control signals, address signals, and write data signals to the DIMMs and receive serialized read data signals therefrom.